Index: clang-tidy/readability/CMakeLists.txt
===================================================================
--- clang-tidy/readability/CMakeLists.txt
+++ clang-tidy/readability/CMakeLists.txt
@@ -19,6 +19,7 @@
   ReadabilityTidyModule.cpp
   RedundantControlFlowCheck.cpp
   RedundantDeclarationCheck.cpp
+  RedundantExternCheck.cpp
   RedundantFunctionPtrDereferenceCheck.cpp
   RedundantMemberInitCheck.cpp
   RedundantStringCStrCheck.cpp
Index: clang-tidy/readability/ReadabilityTidyModule.cpp
===================================================================
--- clang-tidy/readability/ReadabilityTidyModule.cpp
+++ clang-tidy/readability/ReadabilityTidyModule.cpp
@@ -27,6 +27,7 @@
 #include "RedundantControlFlowCheck.h"
 #include "RedundantDeclarationCheck.h"
 #include "RedundantFunctionPtrDereferenceCheck.h"
+#include "RedundantExternCheck.h"
 #include "RedundantMemberInitCheck.h"
 #include "RedundantSmartptrGetCheck.h"
 #include "RedundantStringCStrCheck.h"
@@ -69,6 +70,8 @@
         "readability-misleading-indentation");
     CheckFactories.registerCheck<MisplacedArrayIndexCheck>(
         "readability-misplaced-array-index");
+    CheckFactories.registerCheck<RedundantExternCheck>(
+        "readability-redundant-extern");
     CheckFactories.registerCheck<RedundantFunctionPtrDereferenceCheck>(
         "readability-redundant-function-ptr-dereference");
     CheckFactories.registerCheck<RedundantMemberInitCheck>(
Index: clang-tidy/readability/RedundantExternCheck.h
===================================================================
--- /dev/null
+++ clang-tidy/readability/RedundantExternCheck.h
@@ -0,0 +1,35 @@
+//===--- RedundantExternCheck.h - clang-tidy--------------------*- C++ -*-===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_CLANG_TOOLS_EXTRA_CLANG_TIDY_READABILITY_REDUNDANT_EXTERN_H
+#define LLVM_CLANG_TOOLS_EXTRA_CLANG_TIDY_READABILITY_REDUNDANT_EXTERN_H
+
+#include "../ClangTidy.h"
+
+namespace clang {
+namespace tidy {
+namespace readability {
+
+/// Finds redundant 'extern' keywords
+///
+/// For the user-facing documentation see:
+/// http://clang.llvm.org/extra/clang-tidy/checks/readability-redundant-extern.html
+class RedundantExternCheck : public ClangTidyCheck {
+public:
+  RedundantExternCheck(StringRef Name, ClangTidyContext *Context)
+      : ClangTidyCheck(Name, Context) {}
+  void registerMatchers(ast_matchers::MatchFinder *Finder) override;
+  void check(const ast_matchers::MatchFinder::MatchResult &Result) override;
+};
+
+} // namespace readability
+} // namespace tidy
+} // namespace clang
+
+#endif // LLVM_CLANG_TOOLS_EXTRA_CLANG_TIDY_READABILITY_REDUNDANT_EXTERN_H
Index: clang-tidy/readability/RedundantExternCheck.cpp
===================================================================
--- /dev/null
+++ clang-tidy/readability/RedundantExternCheck.cpp
@@ -0,0 +1,54 @@
+//===--- RedundantExternCheck.cpp - clang-tidy----------------------------===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+
+#include "RedundantExternCheck.h"
+#include "clang/AST/ASTContext.h"
+#include "clang/ASTMatchers/ASTMatchFinder.h"
+#include "clang/Lex/Lexer.h"
+
+using namespace clang::ast_matchers;
+
+namespace clang {
+namespace tidy {
+namespace readability {
+
+void RedundantExternCheck::registerMatchers(MatchFinder *Finder) {
+  Finder->addMatcher(
+      functionDecl(unless(isExternC())).bind("redundant_extern"),
+      this);
+}
+
+void RedundantExternCheck::check(const MatchFinder::MatchResult &Result) {
+  auto* FD =
+      Result.Nodes.getNodeAs<FunctionDecl>("redundant_extern");
+  SourceLocation BeginLoc = FD->getLocStart();
+  SourceLocation EndLoc = FD->getLocEnd();
+
+  if(!(FD->getStorageClass() == SC_Extern))
+    return;
+
+  auto Diag = diag(FD->getLocStart(), "redundant 'extern' keyword");
+
+  if (FD->getLocStart().isMacroID())
+    return;
+
+  StringRef Text =
+        Lexer::getSourceText(CharSourceRange::getTokenRange(BeginLoc, EndLoc),
+                             *Result.SourceManager, getLangOpts());
+
+  int offset = Text.find("extern");
+
+  Diag << FixItHint::CreateRemoval(CharSourceRange::getTokenRange(
+      BeginLoc.getLocWithOffset(offset),
+      BeginLoc.getLocWithOffset(offset + strlen("extern"))));
+}
+
+} // namespace readability
+} // namespace tidy
+} // namespace clang
\ No newline at end of file
Index: docs/clang-tidy/checks/list.rst
===================================================================
--- docs/clang-tidy/checks/list.rst
+++ docs/clang-tidy/checks/list.rst
@@ -224,6 +224,7 @@
    readability-non-const-parameter
    readability-redundant-control-flow
    readability-redundant-declaration
+   readability-redundant-extern
    readability-redundant-function-ptr-dereference
    readability-redundant-member-init
    readability-redundant-smartptr-get
Index: docs/clang-tidy/checks/readability-redundant-extern.rst
===================================================================
--- /dev/null
+++ docs/clang-tidy/checks/readability-redundant-extern.rst
@@ -0,0 +1,13 @@
+.. title:: clang-tidy - readability-redundant-extern
+
+readability-redundant-extern
+=============================
+
+This checker removes the redundant `extern` keywords from code.
+
+`extern` is redundant in function declarations
+
+.. code-block:: c++
+
+  extern void h();
+  
\ No newline at end of file
Index: test/clang-tidy/readability-redundant-extern.cpp
===================================================================
--- /dev/null
+++ test/clang-tidy/readability-redundant-extern.cpp
@@ -0,0 +1,33 @@
+// RUN: %check_clang_tidy %s readability-redundant-extern %t
+
+extern int f();
+// CHECK-MESSAGES: :[[@LINE-1]]:1: warning: redundant 'extern' keyword [readability-redundant-extern]
+// CHECK-FIXES: int f();
+
+extern int f() { return 0; }
+// CHECK-MESSAGES: :[[@LINE-1]]:1: warning: redundant 'extern' keyword [readability-redundant-extern]
+// CHECK-FIXES: int f() { return 0; }
+
+extern "C" int g();
+
+extern "C" int g() { return 0; }
+
+extern "C++" int h();
+
+extern "C++" int h() { return 0; }
+
+inline extern void foo_inline();
+// CHECK-MESSAGES: :[[@LINE-1]]:1: warning: redundant 'extern' keyword [readability-redundant-extern]
+// CHECK-FIXES: inline void foo_inline();
+
+#define FOO_EXTERN extern
+FOO_EXTERN void foo_macro_1();
+// CHECK-MESSAGES: :[[@LINE-1]]:1: warning: redundant 'extern' keyword [readability-redundant-extern]
+
+#define FOO_INLINE inline
+FOO_INLINE extern void foo_macro_3();
+// CHECK-MESSAGES: :[[@LINE-1]]:1: warning: redundant 'extern' keyword [readability-redundant-extern]
+
+#define FOO_EXTERN_INLINE inline extern
+FOO_EXTERN_INLINE void foo_macro_2();
+// CHECK-MESSAGES: :[[@LINE-1]]:1: warning: redundant 'extern' keyword [readability-redundant-extern]